In the third month of pregnancy, pregnant mothers are required to have regular maternity checkups and to apply for a maternal and child health handbook. If the pregnancy risk level is yellow or above, the obstetrician needs to report it. Routine maternity checkups include: i. Measure height and weight, and calculate body mass index to guide nutritional intake during pregnancy and pay attention to controlling weight gain. Blood pressure measurement is a mandatory item in every maternity checkup. If there is an increase in blood pressure, timely intervention should be made. Third, listen to the fetal heart, in the third month of pregnancy the uterus has increased out of the pelvic cavity, at this time the birth can feel the bottom of the uterus on the pubic symphysis, and through the Doppler fetal heart stethoscope, hear the fetal heart in the abdomen, to detect the number of fetal heart, whether it is regular. Fourth, the most important thing in the third month of pregnancy is to do NT under ultrasound, NT refers to the thickness of the transparent layer of the fetal neck, if the NT value is greater than 2.5mm, the fetus has the risk of Down’s syndrome and congenital heart disease, and needs further examination.